Hi and thank you for the suggestion,
I tried the custom size and it did not work. Using custom paper size freezes out all the other print options and gives no control over borders. It fills the page completely and then messes up the tracking for the ribbon passes.
I'm not sure about your printer, but I was having the same problem with my Epson 4000 until I started adding at least .01" margins in the define custom size. (If they are all zero, then it doesn't work.) I was trying to define a 17"x25" paper size. Then the greyed out selections became available and I was able to define new photo sizes (rather than the fill page) in the dialog. The only problem I have now is the one of the margins is about 1/8" more than the opposite margin.